1,873 research outputs found
Inflation as a Strategic Response
In this paper, we examine the effect of increases in health care costs and general inflation on optimal insurance policies and waste in a model of imperfect information with costly auditing. We show that in such a setting, individuals will buy more than full insurance. Moreover, as the cost of medical increases, consumers (i.e., patients) reduce their probability of filing injustified claims, at the same time as insurance providers audit with lower probability. As a result, waste associated with costly auditing is reduced. We also show that a general increase in the opportunity cost of illness (reflected through lost wages due to illness) also decreases the likelihood of false claims, of auditing and thus of waste, but not as much as health care costs increase.
Nous étudions dans ce document de recherche l'impact d'une augmentation des coûts des soins de santé et de l'inflation en général sur le contrat optimal d'assurance médicale et sur le gaspillage dans une économie où les agents-consommateurs possèdent une information privilégiée et où le principal-assureur doit encourir des coûts d'audit pour vérifier l'information des agents. Nous montrons dans cet article que les agents seront plus que pleinement assurés au sens où l'indemnité reçue est plus grande que la perte encourue. De plus, au fur et à mesure que le coût des soins de santé augmente, les agents réduisent leur probabilité de demander des soins de santé injustifiés, alors que le principal réduit sa probabilité d'audit. En conséquence, le gaspillage associé aux audits onéreux diminue. Nous montrons finalement qu'une augmentation dans le coût de la vie en général (que nous approximons par une augmentation des pertes de salaire encourues à cause de la maladie) réduit également le gaspillage associé aux audits,0501s dans une mesure moindre qu'une augmentation du coût des soins de santé.Health care fraud, asymmetric information, contract theory, Fraude médicale, information asymétrique, théorie des contrats
Transdet: a matched-filter based algorithm for transit detection - application to simulated COROT light curves
We present a matched-filter based algorithm for transit detection and its
application to simulated COROT light curves. This algorithm stems from the work
by Bord\'e, Rouan & L\'eger (2003). We describe the different steps we intend
to take to discriminate between planets and stellar companions using the three
photometric bands provided by COROT. These steps include the search for
secondary transits, the search for ellipsoidal variability, and the study of
transit chromaticity. We also discuss the performance of this approach in the
context of blind tests organized inside the COROT exoplanet consortium.Comment: 6 pages, 4 figures, in Transiting Extrasolar Planets Workshop,
meeting held in Heidelberg, 25-28 September 200
Reflectionless measures and the Mattila-Melnikov-Verdera uniform rectifiability theorem
A new proof is given of the Mattila-Melnikov-Verdera theorem on the uniform
rectifiability of an Ahlfors-David regular measure whose associated Cauchy
transform operator is bounded.Comment: 31 pages, 5 figure
Interdigitation between surface-anchored polymer chains and an elastomer : consequences for adhesion promotion
We study the adhesion between a cross-linked elastomer and a flat solid
surface where polymer chains have been end-grafted. To understand the adhesive
feature of such a system, one has to study both the origin of the grafted layer
interdigitation with the network, and the end-grafted chains extraction out of
the elastomer when it comes unstuck from the solid surface. We shall tackle
here the first aspect for which we develop a partial interdigitation model that
lets us analytically predict a critical surface grafting density beyond which the layer no longer interdigitates
with the elastomer. We then relate this result with recent adhesion
measurements
Can neutral and ionized PAHs be carriers of the UV extinction bump and the diffuse interstellar bands?
Up to now, no laboratory-based study has investigated polycyclic aromatic
hydrocarbon (PAH) species as potential carriers of both the diffuse
interstellar bands (DIBs) and the 2175 A UV bump. We examined the proposed
correlation between these two features by applying experimental and theoretical
techniques on two specific medium-sized/large PAHs (dibenzorubicene C30H14 and
hexabenzocoronene C42H18) in their neutral and cationic states. It was already
shown that mixtures of sufficiently large, neutral PAHs can partly or even
completely account for the UV bump. We investigated how the absorption bands
are altered upon ionization of these molecules by interstellar UV photons. The
experimental studies presented here were realized by performing matrix
isolation spectroscopy with subsequent far-UV irradiation. The main effects
were found to be a broadening of the absorption bands in the UV combined with
slight red shifts. The position of the complete pi - pi* absorption structure
around 217.5 nm, however, remains more or less unchanged which could explain
the observed position invariance of the interstellar bump for different lines
of sight. This favors the assignment of this feature to the interstellar PAH
population. As far as the DIBs are concerned, neither our investigations nor
the laboratory studies carried out by other research groups support a possible
connection with this class of molecules. Instead, there are reasonable
arguments that neutral and singly ionized cationic PAHs cannot be made
responsible for the DIBs.Comment: 11 pages, 7 figures, 1 tabl
From single particle to superfuid excitations in a dissipative polariton gas
Using angle-resolved heterodyne four-wave-mixing technique, we probe the low
momentum excitation spectrum of a coherent polariton gas. The experimental
results are well captured by the Bogoliubov transformation which describes the
transition from single particle excitations of a normal fluid to
sound-wave-like excitations of a superfluid. In a dense coherent polariton gas,
we find all the characteristics of a Bogoliubov transformation, i.e. the
positive and negative energy branch with respect to the polariton gas energy at
rest, sound-wave-like shapes for the excitations dispersion, intensity and
linewidth ratio between the two branches in agreement with the theory. The
influence of the non-equilibrium character of the polariton gas is shown by a
careful analysis of its dispersion.Comment: 4 pages, 3 figure
Effective interactions in the colloidal suspensions from HNC theory
The HNC Ornstein-Zernike integral equations are used to determine the
properties of simple models of colloidal solutions where the colloids and ions
are immersed in a solvent considered as a dielectric continuum and have a size
ratio equal to 80 and a charge ratio varying between 1 and 4000. At an infinite
dilution of colloids, the effective interactions between colloids and ions are
determined for ionic concentrations ranging from 0.001 to 0.1 mol/l and
compared to those derived from the Poisson-Boltzmann theory. At finite
concentrations, we discuss on the basis of the HNC results the possibility of
an unambiguous definition of the effective interactions between the colloidal
molecules.Comment: 26 pages, 15 figure
Sliding friction between an elastomer network and a grafted polymer layer: the role of cooperative effects
We study the friction between a flat solid surface where polymer chains have
been end-grafted and a cross-linked elastomer at low sliding velocity. The
contribution of isolated grafted chains' penetration in the sliding elastomer
has been early identified as a weakly velocity dependent pull-out force. Recent
experiments have shown that the interactions between the grafted chains at high
grafting density modify the friction force by grafted chain. We develop here a
simple model that takes into account those interactions and gives a limit
grafting density beyond which the friction no longer increases with the
grafting density, in good agreement with the experimental dataComment: Submitted to Europhys. Letter
Fine structure of exciton excited levels in a quantum dot with a magnetic ion
The fine structure of excited excitonic states in a quantum dot with an
embedded magnetic ion is studied theoretically and experimentally. The
developed theory takes into account the Coulomb interaction between charged
carriers, the anisotropic long-range electron-hole exchange interaction in the
zero-dimensional exciton, and the exchange interaction of the electron and the
hole with the -electrons of a Mn ion inserted inside the dot. Depending on
the relation between the quantum dot anisotropy and the exciton-Mn coupling the
photoluminescence excitation spectrum has a qualitatively different behavior.
It provides a deep insight into the spin structure of the excited excitonic
states.Comment: 6 pages, 6 figure
2D Fourier Transform Spectroscopy of exciton-polaritons and their interactions
We investigate polariton-polariton interactions in a semiconductor
microcavity through two-dimensional Fourier transform (2DFT) spectroscopy. We
observe, in addition to the lower-lower and the upper-upper polariton
self-interaction, a lower-upper cross-interaction. This appears as separated
peaks in the on-diagonal and off-diagonal part of 2DFT spectra. Moreover, we
elucidate the role of the polariton dispersion through a fine structure in the
2DFT spectrum. Simulations, based on lower-upper polariton basis
Gross-Pitaevskii equations including both self and cross-interactions, result
in a 2DFT spectra in qualitative agreement with experiments
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